Abstract
Petalidium konkiepense, here described as a new species, is only known from the Gariep Centre of Plant Endemism in southern Namibia, where it grows on arid hillsides and along drainage lines. Diagnostic morphological characters for P. konkiepense include the rigid, cylindrical distal stems (quadrangular when young), grey or dark brownish grey bark (white to cream when young), densely puberulent vegetative parts with widely spaced robust glandular and eglandular trichomes, and the oblanceolate leaves with prominent midrib and principal lateral veins. A comparison of some of the more prominent features to differentiate Petalidium konkiepense from its morphologically most similar relatives, P. linifolium and P. cymbiforme, is provided. Based on IUCN Red List categories and criteria, a conservation assessment of Endangered under criteria B1 is recommended for the new species.
References
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<p>Swanepoel, W. & Manzitto-Tripp, E. (2022) <em>Petalidium sesfonteinense </em>(Acanthaceae), a new species from the Kaokoveld, Namibia. <em>Phytotaxa</em> 549 (2): 127–135. https://doi.org/10.11646/phytotaxa.549.2.1</p>
<p>Swanepoel, W., Nanyeni, L. & Van Wyk, A.E. (2022) <em>Petalidium mannheimerae </em>(Acanthaceae), a new species from Namibia and South Africa, with notes on the taxonomic identity of <em>P. parvifolium. Phytotaxa</em> 561 (1): 1–13. https://doi.org/10.11646/phytotaxa.561.1.1</p>
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<p>Tripp, E.A., Tsai, Y.E., Zhuang, Y. & Dexter, K.G. (2017) RADseq dataset with 90% missing data fully resolves recent radiation of <em>Petalidium </em>(Acanthaceae) in the ultra-arid deserts of Namibia. <em>Ecology and Evolution</em> 7: 1–17. https://doi.org/10.1002/ece3.3274</p>
<p>Van Wyk, A.E. & Smith, G.F. (2001) <em>Regions of floristic endemism in southern Africa: a review with emphasis on succulents</em>. Umdaus Press, Hatfield, Pretoria, 199 pp.</p>
<p>Anderson, T. (1863) An enumeration of the species of Acanthaceae from the continent of Africa and the adjacent islands. <em>Journal of the Proceedings of the Linnean Society. Botany </em>7: 13–54. https://doi.org/10.1111/j.1095-8312.1863.tb01056.x</p>
<p>Beentje, H. (2016) <em>The Kew plant glossary: an illustrated dictionary of plant terms</em>, 2nd ed. Kew Publishing, Kew, 184 pp.</p>
<p>Burke, A. (2017) Biodiversity zoning in the Greater Fish River Canyon Landscape in southern Namibia. <em>Namibian Journal of Environment</em> 1: 60–71. [https://nje.org.na/index.php/nje/article/view/volume1-burke]</p>
<p>Edwards, D. & Leistner, O.A. (1971) A degree reference system for citing biological records in southern Africa. <em>Mitteilungen der Botanischen Staatssammlung München</em> 10: 501–509. [https://biostor.org/reference/185348]</p>
<p>Figueiredo, E. & Smith, G.F. (2008) <em>Plants of Angola/Plantas de Angola</em>. Strelitzia 22. South African National Biodiversity Institute, Pretoria, 279 pp.</p>
<p>Germishuizen, G. & Meyer, N.L. (Eds) (2003) <em>Plants of southern Africa: an annotated checklist</em>. Strelitzia 14. National Botanical Institute, Pretoria, 1231 pp.</p>
<p>IUCN (2012) <em>IUCN red list categories and criteria</em>: Version 3.1. 2nd edn. Gland, Switzerland and Cambridge U.K., iv + 32 pp.</p>
<p>Manktelow, M. (2000) The filament curtain: a structure important to systematics and pollination biology in the Acanthaceae. <em>Botanical Journal of the Linnean Society</em> 133: 129–160. https://doi.org/10.1006/bojl.1999.0309</p>
<p>Mendelsohn, J., Jarvis, A., Roberts, C. & Robertson, T. (2002) <em>Atlas of Namibia</em>. Philip, Cape Town, 200 pp.</p>
<p>Nees von Esenbeck, C.G. (1832) Acanthaceae India Orientalis. <em>In</em>: N. Wallich (Ed.), <em>Plantae Asiaticae rariores: or descriptions and figures of a select number of unpublished East Indian plants</em>, vol. 3. Treuttel & Würtz, London, pp. 41–117. https://doi.org/10.5962/bhl.title.468</p>
<p>Nienaber, G.S. & Raper, P.E. (1983) <em>Hottentot (Khoekhoen) place names</em>. Butterworth, Durban, 243 pp.</p>
<p>Obermeijer, A.A. (1936) The South African species of <em>Petalidium. Annals of the Transvaal Museum</em> 18: 151–162.</p>
<p>Raper, P.E., Moller, L.A. & Du Plessis, T. (2014) <em>Dictionary of southern African place names</em>. Jonathan Ball, Johannesburg, 566 pp.</p>
<p>Schinz, H. (1926) Acanthaceae. <em>Vierteljahrsschrift der Naturforschenden Gesellschaft in Zürich</em> 71: 145–146.</p>
<p>Sprigade, P. & Moisel, M. (Eds.) (1904) <em>Kriegskarte von Deutsch-Südwestafrika 1:800 000</em>. Dietrich Reimer, Berlin, set of eight maps (<em>Archeia</em> 6; reprint by National Archives SWA/Namibia, Windhoek 1987).</p>
<p>Swanepoel, W. (2020) <em>Petalidium kaokoense </em>(Acanthaceae), a new species from Namibia. <em>Phytotaxa</em> 468 (3): 236–242. https://doi.org/10.11646/phytotaxa.468.3.1</p>
<p>Swanepoel, W. & Manzitto-Tripp, E. (2022) <em>Petalidium sesfonteinense </em>(Acanthaceae), a new species from the Kaokoveld, Namibia. <em>Phytotaxa</em> 549 (2): 127–135. https://doi.org/10.11646/phytotaxa.549.2.1</p>
<p>Swanepoel, W., Nanyeni, L. & Van Wyk, A.E. (2022) <em>Petalidium mannheimerae </em>(Acanthaceae), a new species from Namibia and South Africa, with notes on the taxonomic identity of <em>P. parvifolium. Phytotaxa</em> 561 (1): 1–13. https://doi.org/10.11646/phytotaxa.561.1.1</p>
<p>Thiers, B. (2019) <em>Index Herbariorum: A global directory of public herbaria and associated staff</em>. New York Botanical Garden’s Virtual Herbarium. Available from: http://sweetgum.nybg.org/ih/ (accessed 1 August 2019)</p>
<p>Tripp, E.A., Tsai, Y.E., Zhuang, Y. & Dexter, K.G. (2017) RADseq dataset with 90% missing data fully resolves recent radiation of <em>Petalidium </em>(Acanthaceae) in the ultra-arid deserts of Namibia. <em>Ecology and Evolution</em> 7: 1–17. https://doi.org/10.1002/ece3.3274</p>
<p>Van Wyk, A.E. & Smith, G.F. (2001) <em>Regions of floristic endemism in southern Africa: a review with emphasis on succulents</em>. Umdaus Press, Hatfield, Pretoria, 199 pp.</p>